1. Field of the Invention
The present invention is generally related to semiconductor manufacturing, and, more particularly, to various advanced process control methodologies for thermal oxidation processes, and various systems for accomplishing same.
2. Description of the Related Art
The manufacturing of semiconductor devices may involve many process steps. For example, semiconductor fabrication typically involves processes such as deposition processes, etching processes, thermal growth processes, various heat treatment processes, ion implantation, photolithography, etc. Such processes may be performed in any of a variety of different combinations to produce semiconductor devices that are useful in a wide variety of applications.
In general, there is a constant drive within the semiconductor industry to increase the operating speed and efficiency of various integrated circuit devices, e.g., microprocessors, memory devices, and the like. This drive is fueled by consumer demands for computers and electronic devices that operate at increasingly greater speeds and efficiency. This demand for increased speed and efficiency has resulted in a continual reduction in the size of semiconductor devices, e.g., transistors, as well as the packing density of such devices on an integrated circuit device. That is, many components of a typical field effect transistor (FET), e.g., channel length, junction depths, gate insulation thickness, and the like, are reduced. For example, all other things being equal, the smaller the channel length of the transistor or the thinner the gate insulation layer, the faster the transistor will operate. Thus, there is a constant drive to reduce the size, or scale, of the components of a typical transistor to increase the overall speed of the transistor, as well as integrated circuit devices incorporating such transistors. There is also a constant demand for memory cells or devices with enhanced access times and read/write capabilities.
As a result of the rapid advance in semiconductor manufacturing technology and the performance of semiconductor devices, it is very important that manufacturing processes employed in modern semiconductor manufacturing operations enable the repeated production of semiconductor devices to very exacting dimensions and standards. Even minor variations in processing can adversely impact device performance. For example, in the context of field effect transistors, the formation of a gate electrode to the desired critical dimension is very important. If the critical dimension of the gate electrode is larger than a desired target value, then the transistor may have a lower operating speed than is desired. Conversely, if the critical dimension of the gate electrode is smaller than the target critical dimension, there may be undesirable leakage currents in excess of allowable values. Accordingly, such devices may be less than desirable for many mobile applications, i.e., laptop computers, telephones, etc.
As indicated above, thermal growth processes are employed frequently in the manufacture of semiconductor devices. For example, thermal growth processes may be performed to form a gate insulation layer on a field effect transistor, or a tunnel oxide layer on a memory cell. The formation of such layers may be critically important to the performance of such devices. This is even more true given the continual reduction in the feature size of the semiconductor devices that has occurred in recent years. For example, if the thickness of a thermally grown gate insulation layer or tunnel oxide layer varies from a target value, then the resulting device may not meet target performance characteristics established for such a device. Moreover, it should be understood that, in modern semiconductor devices, such gate insulation layers may have a thickness on the order of approximately 30–100 Å (3–10 nm). Thus, establishing process control techniques that enable a manufacturer to reliably and repeatedly reproduce thermally grown process layers to such exacting requirements is a very challenging undertaking.
The present invention is directed to various methods and systems that may solve, or at least reduce, some or all of the aforementioned problems.